Writing as a former camp follower of John Lillburn's regiment of musket and pike, (English Civil War) when it comes to colours, a vat of strong tea can be your solution.

Even if a dye is correct for the time, the material to be dyed would most likely not have been bleached pure white as usual in modern times, so the end result is also too pure. The use of a browning agent can take a coloured item back several centuries in its tones.

You might already know this, of course, but just in case it can be of any help with getting the right look...

I'm assuming that you can find something suitable in design, but might need to adjust the clarity of the colours, or mabe want to make a garment look - for instance, as though it has been washed in water from a peaty or leafy stream and been affected by the tannin, or that it had belonged to your grandfather, or that you are a roughy toughy outdoor man stained by contact with nature in the raw.

You do need to experiment with the strength of the brew and the length of exposure to it, and remember you can always do another dipping for extra effect, but not so easily undo one that has been too long.